Under the Moonlight
by dolcerefrain
Summary: A sickly weak boy on this deathbed wishes for freedom. A starving vampire wishes to quench his thirst. Vampire!Ryuu x Diseased!Sougo AU; Non-canon.
1. Prologue

**Disclaimer: I do not own iDOLiSH7 or any of its characters.**

* * *

 **INTRODUCTION**

 _ **SOUGO**_

"All finished, Osaka-san."

Sougo silently brushed his slender fingers on the spot where the nurse had drawn his blood from. It was slightly aching, but the young boy didn't mind the pain. He was already used to the sensation of needle piercing through skin - and he'd admit that it feels nice sometimes.

To be frank, even if he was cured from this illness he was suffering from - which is impossible, as it was terminal; he would probably take up a hobby of poking himself with needles just for his own enjoyment. To him who can barely move from his hospital bed, pain was a spark, a light burst of sensation that sends shivers down his spine, one which spices up his dull life.

It was something that reminds him that he is very much alive, despite his condition which one could describe as good as dead.

"Thank you very much," Sougo mumbled politely. As always, his eyes remained fixated on the landscape on the other side of the windowpane - illuminated trees weaving through the streets, the faint honking of cars from the lively city, and the glittering lights of towering skyscrapers.

The more he stares upon the view before him, the more his yearning to escape, to be enveloped by the blinding lights and deafening noises grows. It is painful to think about such a thing - a different kind of pain than the one he enjoys. It is a subdued pain that swells deep inside his chest, the pain of knowing that everything he wishes for will never come true, that his life will become empty and worthless in the end.

 _How hopeless._

"It must be boring to always be stuck to a hospital bed," the nurse commented with a soft chuckle, her voice void of any ill intention, as she noticed Sougo's longing gaze.

"I suppose there's an opportunity cost for everything," Sougo let out a dry laugh, refusing to answer the said inquiry directly. As always, his eyes did not leave the dazzling sight beyond him. "Aren't I pitiful?"

"Not at all," the nurse replied without hesitation, as she arranged the medical equipment neatly in a steel box. The conversation lulled for a moment, with the only sounds in the room being the beeping of the machine attached to the IV drip Sougo was hooked up to, and the clinking of metal from the nurse putting her tools away.

"I'll be taking my leave now," the nurse spoke up, interrupting the silence in the room. Sougo turned around to give her a polite nod, paired with a small smile.

"Thank you for your work."

"It's my pleasure, Osaka-san." The nurse bowed slightly, flashing him one last smile before turning around and pushing her cart out of the room.

When Sougo heard the door close with a click, his smile immediately dropped away from his face. His eyes fluttered around the ever-so-familiar room - if there were no medical equipment or machines around, one may see it as a location from a luxurious hotel. It was a five-star hospital suite, complete with a cosy living room area, a large balcony, and even a separate spare bedroom. Various still-life paintings adorned the wall, unpleasantly similar to the ones in his family's mansion. It was too large for two people - Sougo himself and his butler, which makes him uncomfortable. He doesn't _need_ half of the room's space, considering the fact that he's too exhausted to even get out of bed.

 _Like everything else, all of this is just wasted on me._

The young man let out a sigh and rolled over, whilst trying his best to subdue his negative thoughts. His eyes rested on the pure white lilies beside his bed that his father had sent him the day before, sitting in a fragile violet vase. Sougo liked lilies - they are such a delicate flower - beautiful, yet simplistic. Glorious, yet one could still describe it as a humble flower.

However, the ones beside him were starting to be stained with brown splotches, slowly rotting and dying.

 _Just like me._

He sunk into the pile of pillows on his bed, turning his attention back to the window. It was already very much late, but the city's liveliness hadn't died down, not even a bit. A small bitter smile appeared on his lips. Wishing for himself to be cured wouldn't help with anything - he won't ever heal, he won't able to live normally, and he won't be able to step outside and get the taste of the world. That's just how it is. No matter how tired he is with living his life like this, it is the only way that would keep him alive.

But tonight would be different.

Tonight, he will not be lying in his bed, torturing himself with dreams that would not come true.

Sougo slowly sat up, stealing a glance at his blond-haired butler. He was sprawled out on the violet sofa beside his bed with a catalogue of anime goods resting neatly on his face. One of his arms were dangling down on the side of the sofa, while the other lay neatly on his stomach. The lilac haired man let out a small chuckle. He probably worked especially hard today - normally the butler would always make sure Sougo is all tucked in and comfortable before going to sleep himself.

"Nagi-kun? Are you awake?" Sougo murmured gently, despite knowing the answer himself.

As expected, his question was answered by the blond's soft snores.

 _Perfect_.

The silver-haired man swiftly yanked the needle of the IV drip out of the back of his hand, and lowered himself out of the bed. He shuddered slightly as his bare foot came in contact with the cold tiles, but the coolness was immediately subdued by the discovery of his hospital slippers. With a fair amount of struggle, he managed to walk all the way over to his closet and change out of his ugly green hospital gown to a white dress shirt and long formal black pants.

Being born as the heir of the Osaka household - one of the richest families in Japan, he was considered lucky by many. However, Sougo had contracted a chronic illness when he was only two of age, and it affected his immune system badly. Due to his poor health and weak physical strength, he was forbidden to go outside, and was confined within his hospital room for the past 18 years.

His father is always busy with work, so he doesn't bother to drop in to check in on Sougo's condition much. Besides Nagi and his home tutor, he didn't have any friends or acquaintances (if you don't count those greedy businessmen that his father sometimes introduces him to), and the only world he knows of is this white-walled room that he was trapped in. It was so achingly empty - so suffocating to live like this for so long. He spends his days quietly reading books and encyclopedias, his interest seeming to zero upon books about bonds with other people, different cities around the world, and current affairs.

It is nice to at least have a connection to the outside world this way, but it's not enough for Sougo.

It's not like he was going to live forever. Sougo knew well that his days were numbered, and he refuses to pass on peacefully after wasting most years of his life trapped in an empty hospital room, constantly staring at white wall and being restricted to his bed, of constantly having to acknowledge that that despite all the riches and privileges he has, his hopes and dreams were nevertheless stolen away by his illness.

After making sure he put everything on neatly, Sougo limped weakly over to his butler, poking him ever so lightly to make sure that he won't wake up. After a few more tries of poking with no response, Sougo quickly leaned down to whisper,

"I'll be back."

The goodbye ending with a light touch from his fingertips.

* * *

 **A/N:**

 **Hello! This is my first fanfic after a 4 years' hiatus, so I hope you enjoyed it!**

 **I've been developing this AU for a bit now, first wanting to make it a VN but I'm too busy to complete it OTL**

 **Thank you for reading!**


	2. Chapter 1 - Hors d'oeuvre

Chapter 1 - Hors d'oeuvre

 _ **RYUUNOSUKE**_

Ryuunosuke let out a small cough as he walked through the crowded streets. The sound of beeping cars and the distant chatter around him was ringing in his ears, as if it were white noise.

 _I have to get out of here._

He pushed through the crowd, trying to avoid eye contact, both of his hands clutching tightly on his black coat to ensure that he has his hands to himself. It was suffocating - this is why he despises coming outdoors - the loud noises and the presence of crowds has always been unbearable for him. If it weren't for Tenn asking - rather, forcing him to run one of his odd errands, he wouldn't have stepped outside the manor.

Usually, he would complete his job and soar home immediately, which made him able to avoid such situations before. But today was different. Ryuunosuke ran his hands through the interior pockets of his coat to make sure he wasn't mistaken, that perhaps there was something in there that he had missed.

Empty.

His stomach growled with hunger just by thinking about the contents of what it is usually filled with - bottles of animal blood, fresh and warm from the blade of Tenn's hunting knife. He ran his tongue over his silver fangs, wishing to taste it right at this moment, right now. If he had the blood, if he just had a little snack, he was sure he would be able to replenish his energy and fly straight home. Well, he is technically surrounded by food right now.

But there was no way he was going to drink blood straight from a live human being.

Fatigue shot through his body, every one of his limbs as heavy as lead, and his head throbbing with pain. The sight of the people around him, the warmness of the crowd's body heat, the fact that the arm that just brushed through him was filled with that delicious, crimson liquid - all of that was making him lose his mind. He's hungry, he wants blood, and it's just all in front of him.

 _Just grab someone and feed yourself_ , a voice in his head piped up. _It's better to do it while you still have your head cool._

"But that's wrong," the brunet whispered under his breath as a reply, his eyes darting around him to find an escape from the mass of people

Ryuunosuke himself wouldn't take the risk of assaulting someone in public - he had to escape from the crowd. He decided to take a detour around the busy streets, and take another route. Fortunately for him, there was an empty alley connected to a private hospital nearby. He'll have to go around the hospital and this would take him more time to get home, but it was better than him taking the risk of rushing through his food while famished.

Tenn would probably make fun of him for this, but he'll admit that being around people really does scare him. It's not the people themselves he fears of - he's rather more worried of what he might do if he loses all his rationality.

The last thing he would want to do is to hurt someone again.

The vampire shuddered at the thought. He could not make himself inflict harm towards a human being - the look of horror in their eyes as they realize what he is, the pain they have to endure when as fangs puncture their skin, all while in a state of confusion - the thought of that wounds him. It wasn't fair for them to suffer for his own needs. Just because they were at the wrong place at the wrong time, doesn't mean they have to experience such a thing.

As a child, it always bothered him, but he had no choice, did he? He regretted it badly, but had to continue the act anyway. At least, not until he met Gaku and Tenn, and found a substitute to doing so. Tenn - the one and only Kujou Tenn - had offered to find him animal blood (Ryuunosuke doesn't ask where or how he gets it) in exchange for his labour. From that point on, he had been living peacefully with the other two in a manor deep in the mountains, with no need to worry about his food.

For thousands of years, he had relied solely on animal blood. But it is not enough - it's like being a meat-lover turned vegan. Vegan meat can never substitute real meat perfectly. You'll still have a yearning for the real thing. Likewise, there's still a small part of him that wants to taste that pleasant flavor again - the sweetness of human blood.

As he wandered through the alley with his heads buried in his thoughts, he suddenly bumped into something soft and slightly cold.

It was a young boy - a boy with hair as white as snow, skin as pale as porcelain. The moment he laid his eyes on him, Ryuunosuke forgot about his hunger for a moment - the young man's beauty pierced into his heart. Despite the worn out look on his face and his crumpled dress shirt, there was still a trace of elegance in his appearance.

Ryuunosuke tried to make words of apology come out of his mouth, but they were stuck at his throat. Maybe he's not correct, but the coolness of the boy's skin, his unnatural beauty...

It was as if the boy in front of him wasn't human.

"A-Ah, I apologize," the silver-haired stranger quickly whispered in a shy, hushed voice, panic filling his beautiful violet orbs.

Oh, the vampire thought, almost letting out a sigh of admiration. _What a sweet voice he has._

A pleasant voice, an attractive face, the embodiment of beauty itself…

…Is this boy a siren? He had heard stories about those from Gaku, but have never encountered one before. No - sirens are supposed to be out in the sea, right?

If so, then what on earth is he?

"S...Sir? Are you alright?" The sugary voice rang out again, snapping Ryuunosuke back to reality.

He blinked once, twice, before scratching the back of his head awkwardly, mustering out a reply. "I...It's not your fault. I wasn't looking where I was going. Sorry."

As the beauty bowed down slightly as an apology, the smell of lilies wafted through the air, making Ryuunosuke shudder. He could feel his heartbeat quicken, his brain not able to assemble any thoughts.

Is this boy trying to charm him?

The vampire bit his lip, trying his best to not let himself get dragged along with the boy's beauty. The smell of flowers; was he one of the fair folk? Perhaps luring for a victim like him?

Maybe that is so. Tenn had once advised him to not mess with the fair folk after one nasty encounter, so maybe the best thing he should do is run and without looking back.

But Ryuunosuke found himself frozen, his eyes fixated to the mysterious being before him. Maybe it is because of his exhaustion, or maybe it was because of the boy's charms that he is unable to process any thought. Beneath the bewitching moonlight, the boy's ashen body seemed to be glowing. His head started to spin as he watched the boy nod politely and run his hands through his hair, exposing his pale, white nape.

 _Bite him_ , a voice in his head whispered. _Just bite him, and you would be relieved of your hunger._

'But I don't want to hurt him,' Ryuunosuke's voice of reason echoed back.

 _Just a little bit of blood couldn't hurt, right?_

 _If you don't bite him now, you'll not make it home._

 _Besides, if you don't attack him first, perhaps you'll be the one who becomes prey._

"T-Then, I'll be on my way -" As the boy's delightful voice rang through the vampire's ears, his rationality shattered into pieces. Maybe it was his sense of self-preservation, maybe it was the boy's charms, or maybe it was his hunger that caused him to lose his mind. He had no idea.

The only thing he remembered was grabbing the boy's fragile wrist, and flinging him into the brick wall.

* * *

 _ **SOUGO**_

Everything was going well.

He barely managed to escape from the fire exit, and he was just heading through the shortcut he studied beforehand, towards the city centre. If only he left a bit earlier, or a bit later, maybe he wouldn't have to encounter this dangerous-looking stranger.

Sougo shuddered, his body frozen in both terror and fear. His wrists were aching from the pressure the stranger was applying. The tawny, amber eyes staring down at him was the eyes of a predator staring at its prey, filled with madness and hunger.

Sougo stared back up at those cat-like eyes meekly, as if begging for the stranger to let him go.

 _Is this what they call "mugging"?_

Sougo had read articles about such situations. It is mostly done in order to force a person to give up their possessions, if he remembered correctly. He may be the son of one of the richest millionaires in Japan, but this mugger chose the wrong target - he didn't have anything with him but a bent paperclip he planned to use when sneaking back in his room.

To be frank, he found crime an interesting experience he wants to face in some point of his life, but he didn't expect to face it immediately after being able to step outside!

The young boy shakily inhaled crisp night air, doing his best to clear his head and empty the stuffiness of his lungs. He quickly tried to stutter out a string of words, hoping the criminal before him would let him go.

"S-Sorry, but I don't have any money on me..."

However, the stranger didn't budge. As Sougo was planning to repeat himself again, thinking the tall man didn't hear him, the brunet leaned down and buried his face in the crook of Sougo's neck.

 _Huh?_

The young boy froze, trying to process the situation he is in. He tried to push away the stranger, but his weak physical strength didn't help much.

 _What a weird way of mugging_ , Sougo thought, while still doing his best to squirm within the other man's grasp. The man suddenly let out a deep growl in the midst of his attempts.

Sougo abruptly stopped moving, fearing he would anger the other. Before he could say anything else, however, he could feel the other man's ticklish breath on his neck. And before he knew it, he was blinded by a hot, piercing pain.

It was different from the pain he was used to - the quick and delicate prick of needles - this is way more intense. His mouth was hanging open in a silent scream, eyes widened in agony. It was as if something sharp and thick was embedded into his skin, sucking away his energy…

 _A vampire?_

He had read about them in books - monsters of the night that consume human blood. Aren't they supposed to be fictional? He had only heard of them in stories, not history books - If he knew vampires exist, he would've taken more caution in sneaking out at night.

Sneaking out was a bad idea, his subconscious chided, while Sougo found himself unable to move his body. It was as if all his limbs became frozen, immobile. At that point, only one thought ran through his head.

 _I'm going to die._

 _I'm going to die. I'm going to die. I'm going to die._

 _I'm going to die. I'm going to die. I'm going to die._

His legs were starting to shake due to his depleting energy, as if he were about to collapse. After a short while, they gave in - Sougo's knees buckled, and he crumpled to the ground - would've crumpled to the ground, if not for the strong arms wrapping around his waist to prevent him from doing so.

The coldness of the vampire's arms, his hot breath on the crook of his neck, the resonation of gulping sounds...

That was all he could sense as his vision started to get hazy.

 _I don't want to die._

He gathered the last bit of his strength to try to push the stranger back, despite knowing that it was futile. But he still fought for his life, the life he never wanted, until his vision has been completely engulfed with darkness.

* * *

 _ **RYUUNOSUKE**_

Once he sunk his fangs into the other boy's neck, all his mind could focus on was the sweet flavor of blood dancing on his tongue. He drank and drank, like a thirsty child greedily drinking his milk. Even though he had enough to quench his thirst, he couldn't stop himself from indulging himself more in the sugary treat - so he continued drinking, until his hunger has been entirely subdued.

As for now, the energy in his limbs has been fully restored, and if he were to be frank, he feels the most refreshed in a thousand years. Despite that, the culpability from his actions were starting to swell up as his eyes laid upon the unconscious boy in his arms.

So he _is_ a human.

Ryuunosuke took a closer look at the boy, his eyes filled with admiration and awe. Even when unconscious, the word 'beautiful' wasn't enough to describe him. His long lashes were perfectly curled on top of his closed eyelids, locks of silver hair slightly messy, but pleasing to the eye nevertheless.

 _To think I mistook him for a siren._

He reached over to the boy's wrist, intending to check his pulse. Hopefully, he didn't overdrink…

If he did, then he wished Tenn knew a thing or two about necromancy.

Once his fingers touched the boy, however, he was greeted by the feeling of plastic against his skin. Ryuunosuke looked down, and found that the boy was wearing a plastic band on his wrist.

 _Ousaka Sougo, Room 1005_

"Ousaka Sougo-kun..." Ryuunosuke mumbled the name to himself quietly, his voice filled with endearment. It was a charming name that suited a beautiful person such as Sougo himself, and he couldn't help but love how the name rolled out on his tongue.

Despite that, his affectionate demeanor was quickly replaced by his guilty conscience once his eyes settled upon the red marks that was tainting the boy's pure white skin.

 _To think I hurt such a delicate person - a sick one at that...poor Sougo-kun._

There was no way the vampire would leave him lying on the ground, unconscious and defenseless. At least, to atone for his actions, he should return him to where he came from.

Ryuunosuke carefully scooped the boy up, and leaned down enough for his mouth to line up against the sleeping beauty's ear.

"I'm sorry."

His whisper dissolving into the darkness, as he leapt up towards the great starry sky.

* * *

 _ **SOUGO**_

"-san. Ousaka-san, please wake up. It's time for your daily check-up."

When his eyes opened up to see the familiar ceiling of his hospital room, Sougo quickly shot up from the bed in a panicked state.

 _I'm alive._

"What's wrong, Sougo?" his butler's voice was full of concern, eyebrows scrunched as he leaned in to take a closer look at his master. "You seem... strangely alarmed. Are you alright?"

Nagi's touch against his skin was gentle and warm - this is real, all of this is real.

He _is_ alive.

"It's...just a nightmare." Sougo managed to breathe out. A very vivid nightmare indeed. "What time is it?"

" _Oh_ , Sougo," the blond sighed, gently clasping Sougo's hands with his. "It's one in the afternoon. You slept like a log; I was worried for a bit there when you didn't wake up, even when I was shaking you."

Sougo looked down at his hands, and realized he was in his hospital gown.

Was all of that really a dream?

One of his hands snaked towards the crook of his neck, the spot where the vampire bit him.

The absence of pain told him the answer he needed.

"Osaka-san? Is something wrong?" the nurse inquired, leaning over to look at his neck. "Does your neck hurt?"

"No," Sougo smiled gently at her, letting his hands fall back into Nagi's grasp. "Not at all."

* * *

 **A/N:**

 **This took longer than I thought aaaa**


End file.
